MOF-Based Photonic Crystal Film toward Separation of Organic Dyes.

Metal-organic framework (MOF)-directed photonic structure materials have inspired great attention for extended and enhanced functions. However, the direct construction of photonic crystals (PCs) with MOF particles as building blocks still remains a challenge. Herein, we designed and synthesized monodisperse polyamidoamine (PAMAM) dendrimer-modified zeolitic imidazolate framework (ZIF-8) particles (PAMAM@ZIF-8) via a postsynthetic method, rendering ZIF-8 with hydrophilicity. It was found that the PAMAM@ZIF-8 particles could directly assemble into a uniform photonic structure and effectively suppressed the coffee-ring effect, forming homogeneous PC films with different structural colors. A PC pattern with angle-dependent colors was also achieved, which might have potential applications in the field of anticounterfeiting printing. More importantly, by taking advantages of a membrane separation-assisted assembly process, a colorful and robust PC film was accomplished on the surface of reduced graphene oxide (rGO). The hierarchal PAMAM@ZIF-8/rGO film demonstrates a superior separation ability toward organic dye solutions, which enriches the function of PC materials. This work gives a new insight into the fabrication of MOF-based functional PC materials, which will extend the application of PCs in the high selective and effective separation field.